This invention is generally concerned with a load current control circuit, and more particularly with a current control circuit for a load including means for limiting the current therein.
As discussed in the related Patent Application, it is desirable to provide a current control circuit including provision for controlling the motor winding current of a brushless motor, such that the high acceleration and starting torque demands made on the motor in a given motor application may be met, while protecting the motor winding against thermal overloading. In this connection it is noted that in order to achieve high acceleration and starting torque values, the motor winding current may be peaked at a value which is an order of magnitude greater than the rated current value, so long as the peak value is not maintained for a time interval sufficient to permit the motor winding to reach the thermal breakdown temperature on which the rated current value is based.
In the course of providing the aforesaid current limiting circuit in the environment of driving a brushless motor, it became apparent that there were numerous additional engineering applications wherein the current limiting circuit is useful. For example, to control the current delivered to any inductive load, driver or other load, in an application which normally calls for the provision of a continuous current value in the load and intermittently calls for the provision of a peak current value therein.
With the above thoughts in mind, in accordance with the present invention there is provided a current limiting circuit which is useful in the motor application shown and described in the aforesaid related Patent Application. More generally, the present invention provides a current control circuit which preferably includes structure for monitoring the current in a load with a view to limiting the continuous current values therein to values within the range of a predetermined high value and a predetermined low value to ensure that the continuous current value does not exceed the continuous peak current value rating of the load, whereby peak current values may flow in the load for short time intervals to accommodate the high current demands of the load.
Accordingly:
an object of the invention is to provide a current control circuit for a load, and
another object is to provide a load current control circuit including means for limiting the average or RMS value of a voltage proportional the average or RMS value of continuous current in the load, to a value which is between a predetermined high current value and a predetermined low current value, whereby the continuous current value may be intermittently peaked.